<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <button id="btn">click</button>
  <script type="module">
    document.querySelector('#btn').addEventListener('click', () => {
      import('./app.js').then(result => {
        console.log(result)
      })
    })
  </script>
</body>
</html>